This invention relates to power modules and more specifically relates to a low cost 3 phase inverter module which has no substrate for the power semiconductor die.
Power semiconductor modules are well known and are widely used. Typically, a plurality of semiconductor die, such as MOSgated devices, thyristors or diodes in various combinations are mounted on a substrate heatsink, such as an IMS (insulated metal substrate) or other substrate and are electrically connected through the substrate, and/or by wire bonds, to form a particular circuit. A printed circuit board containing low power control components is also supported by the module. Power and control terminals may then extend from an insulation housing which carries the substrate.
Substrates used to carry the power die constitute a significant part of the cost of power modules, and therefore they are limited to the smallest possible area. It would be desirable to reduce the cost of such modules while permitting appropriate thermal management and electrical insulation.
In accordance with the invention, the power die are mounted directly on lead frame extensions of a lead frame which is insert molded within and supported by the module insulation housing. A heat conductive insulation layer underlies the lead frame elements to insulate it from a heat sink support for the module. No added IMS or other substrate is used, thus reducing the cost of the module.
In a preferred embodiment, the module is a three phase inverter circuit for automotive application for example, for electric power steering motors. However, any other desired circuit can be provided.